Funny you should mention that. I'm working on a website that should help answer those types of questions
I have some Federal Hydra Shock in my mag right now. That was a pricey $18 for 20 rounds but I got it at a local gun store. I then got a bunch of 50 round boxes from New Outdoors Man ( http://www.outdoormarksman.com/index.php?cPath=65) . Some JHP, some FMJ, just to try them out. I was quite surprised to find that one type actually wouldn't feed reliably, Winchester 180 Gr JHP jammed 3 times out of 47. Yesterday I fired 47 rounds of Federal Classic self defense, no problems.
Basically to be sure your 990 likes your ammo you'll have to try a few kinds and shoot a significant number of them to get confidence. Looking at the various JHP ammo I got I'm not sure it's worth the extra $$ to get 'high end' but only gelatin tests would a real test short of shooting someone.
Order a variety pack of ammo and head to the range!
I have my self defense mags loaded with Federal 124 gr +p Expanding Full Metal Jacket (EFMJ) rounds. I like the expansion and penetration properties and they seem to be less susceptible to the "clogging" that can happen with the tip of JHPs.
I did a little "experimenting" with EFMJ a while back. I put the results on my website, here: http://users.adelphia.net/~navy87guy/ballistics.html I ran about 300 rounds through 6 different pistols (50 each) and I didn't have a single problem with feeding or firing.
I bought 500 rounds of the stuff from Ammoman for $175 (delivered). Quick service, too (ordered on Sunday, delivered on Wednesday).