what is your favorite brand for .25 and .30 cal airguns?

Typically you get what you pay for. The caliber will probably depend on what you want the gun for. 

I choose guns that are either easy for me to work on myself, or I have a local dealer that will stand behind their product. 

I have a .22 Kalibergun Cricket Mini Carbine that I absolutely love. Also have a Power Tunned .25 KG Cricket it hits HARD! At 62FPE. Other guns and brands will serve you well, as owners will testify. 

I would say, buy the best you can afford. Try to buy local if you can. Hope this helps. 

Also, try to narrow your choices down a bit and do a search on this site and others. Most owners will have posted their results already. 
.25 is cheaper ammo than .30, wastes less air. More shots per fill, etc. Good shot placement will trump powe in most or all cases. 

With either the FX Impact, or Crown you can run both .25, 30.

Although I took a lit of game with my Crown, I decided to dedicate it to benchrest. I just purchased an Impact for hunting. Both .25

After I get used to the Impact I will be getting one of the new 700mm .30 barrel kit, for larger game.

The .25 was just perfect for taking large woodchucks, and the accuracy of the Crown ensure only one shot. I'm using the 33.9gn MKII JSB pellets at 840fps

Preference for me is shaped by my early career (Machinist). I don't feel like anyone makes an air rifle which is perfectly suited for me from the factory. There are some amazing airguns out there that check about 95% of my blocks, but not all. So my big "button" is "what can I modify to check all of my boxes". Although there are many airguns which come from the factory as amazing performers, the one which has the largest and best list of modifications still remains to be the Benjamin Marauder. For those who don't want to modify, I fully understand why they gravitate to other air rifles.

Top of your price go RAW in .25.
Tons of down range power and the largest cal. that still sits ( reasonably) still when firing. .177 through .25 you can pretty well just lay it on a bag site & fire, you hit the target and be off the sight a bit, .30 & up dont try that it NEEDS to be held still and recoil- ya slight but- dealt with.
With the new HEAVY .22 ammo available a .22 can 100% match the .25, check into that one, it'll give you more to consider esp. if you like figuring BC & such.
Did I say I had the .30? Love the .22.

Now lower priced, go used! Grab a Career 707II in .25 , insane power - 999fps w/39.4g Pelletman solids. Dial the power wheel down 4 clicks before starting, fire 6 click up 4 , fire 6 for a 40fps spread. Best varmit shot a legal Bobcat with Chicken in mouth at ( measured w/tape later ) 67 yards using Korean heavies. Heavies were better for target and safer for varmint. Night raccoons at 40ish yards clean kills always.


The Sumatra ( currently available) might be a option if needing max power.
John

EDgun I think is the best easy to work on great video help show you how to do things. very few other company's do what they do. And they shoot great

I have a Career 707.22. Real close to the Sumatra gun. My first PCP. I love the ability to rotate the power wheel and shoot from 600fps, to over 1200 fps. I started using Crosman Premier 14.3gr dome pellets at 900 fps. The Career 707 was known for its accuracy. I was getting about 90 shots per fill. Max distance was shooting was about 75yds. A buddy who also bought a Career 707 when I did started talking about heavier pellets. We started shooting 18gr Beeman pellets. then 21gr Beeman pellets, out to and over 100 yards. The gun is amazing. I saw no reason to make a change. I shot that Career 707 for years. Using the heavy Korean pellets, it would stack pellets on top of one another at 25 yards. This is with a non reg gun. Then I see this kid on YOUTUBE shooting a .22 Edgun. Here was a guy hunting as I was. He had his Edgun, and I my Career 707 topped with a Centerpoint 4-16x40 from Walmart. The Career 707 NEVER let me down. Then this kid gets a .25 and posted a video. I let my buddy know of the video.

All was well, but we had target rich environments in which to hunt. With the power of the Career 707, pass through shots were often. So we looked at YOUTUBE and decided we wanted accurate guns, lots of shots, and better glass.We ordered a couple of BSA R10 MkII .177`s. Nice guns. but we only got around 48 shots. Ordered two larger air tanks, shot count went to 90. We hunted, and hunted hard. I love head shots, and the R10 delivered. I still watched this kid on YOUTUBE. He was very good at explaining what he did, and how he did it. A year later I ordered a Kalibrgun Cricket .25. I mounted an Athlon Argos 8-34x56 mil/mil on it. Ishot, and still shoot 25.4gr JSB pellets. I have made some incredible shots, kills, hunting was soooo fun with this much power. I would rest the Cricket on a 2-7/8" fence post and shoot ground squirrels. A compact gun, powerful, accurate, and 4 spare in the stock. i did not need to load mags anytime soon. I was able to stretch my shooting out to 120 yards and feel comfortable. That damn kid on YOUTUBE, he is making some awesome videos.

I watched more YOUTUBE videos. Then got the urge to shoot longer distances. Reading on this site,YOUTUBE, a couple more sites and the new gun bug bit me. 
I knew I wanted a .25 cal gun. That kid again, the FX Crown had me, but was not easy to come by. I ordered a .25 Crown. I wanted a gun that had more power than my Kalibrgun Cricket. The videos of Ted, Matt and others with the FX Crown won me over. BUT I wanted more power. I was told there was a 30 day wait to get an FX Crown as they were back ordered. Started reading about the RAW HMX1000 .25. Watched some videos, and the tour of Martin and the workers.I cancelled the FX Crown order, ordered a RAW HMX1000 LRT .25 @ 60 foot lbs. I wondered if I made a mistake ordering the RAW. I still watched FX Crown videos. A video or two came out on the RAW HMX1000 .25. Guys on this site were going through the same emotional up and downs as I was. 12 weeks later, I had the finest airgun I have ever held in my hands. 

I mounted an Athlon Argos 6-24x50 MOA scope on the RAW. I have not benched the gun. I hunt. JSB hvy MkII2 are my go to pellet. At 60 ft lbs, they kick up dust when passing through a ground squirrel inside of 50 yards. Was in contact with a guy that makes HP Slugs. Ordered some slugs off Ebay. At 52 yds, when that HP slug hits, it is LOUD. NOTHING hit with this HP Slug has escaped. They are DEVISTATING. So far, my longest confirmed kill has been 120 plus yards with JSB 33.95 gr MkIIs. I can and do regularly head shoot ground squirrels at 80 plus yards. I love my RAW.

Tom, I HUNT. I love POWER. I like the Crown. I do not get excited about fiddling with multiple adjustments. I like simple. Never handled a Crown. No regrets. 
I understand not liking bull pups. The extra fps with the JSB heavies makes for flatter trajectories. The RAW HM1000X will shoot 1/2" groups at 50 yards, IF the shooter can do his part. IF you get a RAW HM1000X .25 W/POLLY barrel, make sure to buy some slugs off Ebay. They make a mess of things.

Tom, when I was looking, there was not much price difference between the RAW and the FX Crown. Never considered the Streamline.