The 22" is what most people, including myself use. Some, particularly commuters who need to pack for more days, like the 26" but it is heavy. Anything over 22" will pose a problem for deadheading or pass travel on CAL since it won't fit in the overhead compartment.
If anything I wish they had a 20".
The Luggageworks 22" Stealth NG is what I have and is worth every penny of the substantial price. You'll get lots of opinions on luggage, but I bought the best and have never worried about it breaking.
I had their ballistic flight kit and it was great for 2 years, then it fell apart. Under the ballistic nylon is essentially cardboard, and it got wet several times during the summer monsoon in Houston. The cardboard basically dissolved, leaving me with a duffel bag.
The leather flight kits are nice ( I have a Coyote Works bag) but are very expensive, and something you can get once you're off first year pay. Or they make nice Christmas presents.
Coyote Works comes to the new hire classes and does payroll deduct, so many new hires buy them once they get here.