I haven't seen all of those movies, but the ones I have are all worth seeing.
But here are more specific opinions for them:
Night School - I do really like this movie, but it's not one I revisit often. Absolutely worth seeing if you're a fan of the slasher genre, but maybe not worth owning.
Killer Party - I think this movie is just SO MUCH fun! It definitely has flaws and is kind of all over the place, but it's very entertaining and re-watchable. I love the three main girls, and the end credits song is extremely catchy. Buy it!
Mortuary - Very underrated. Atmospheric and fun. Scorpion's disc is terrific too (the transfer is beautiful). Rumor is it will be coming to blu-ray soon, so I'd hold off until then. But when it does, buy it!
Silent Scream - Kind of a slow burner, but very good. Along the lines of Ghost Keeper or The Unseen, if you've seen either of those. And another terrific disc from Scorpion, I don't think I even made it through all the interviews there were so many. But like with Mortuary, there are rumors it is coming to blu-ray. So I'd hold off. There isn't a ton of replay value, but the disc itself is strong enough to recommend.
Evil Laugh - Another one that is just FUN FUN FUN! Really dumb, but extremely entertaining. I always crack up when Steven Baio pees on that random guy. The quality on the DVD isn't great, but it's loaded with enough extras to make up for it. Buy it!
Girls Nite Out - I didn't like this at all the first time I saw it, but I admit the ending was creepy. Watched it again recently and LOVED it the second time around. I've seen the DVD for $1.97 at FYE recently. Tough to recommend, but if you can find it for $1.97 then buy it.
Funeral Home - William Fruet is extremely underrated. Not as much fun as Killer Party or as engaging as Trapped and Death Weekend, but still a fun little movie. Very much an '80s teen version of Psycho.
The Final Terror - Very atmospheric backwoods slasher. Absolutely worth checking out. Fun, and even occasionally creepy. The sex scene is a strange one as far as '80s slashers go, since you see more male skin than female. Would love to see a cleaned up version of this movie, I still have it on VHS. Buy it!
Night of the Comet - Shamelessly fun and incredibly rewatchable. Scream Factory's upcoming blu-ray should be amazing. Buy it!
Sole Survivor - Very underrated little movie. It's not one I rewatch very often, but it's absolutely worth seeing. If you can find the DVD for a reasonable price, go for it.
Deathdream - Bob Clark. Need I say more? Buy it!