How many opinions do you want? Everyone will have a different one on this subject!
Personally, I have heard too many accuracy issues with the Hanna Calcium, Salifert Alkalinity, and Elos Mg to spend money on those particular kits. I have personally experienced more than one Salifert Alkalinity kit to be off by 1-2 dKH.
Kits that I do like include: Elos for calcium and alkalinity, API for alkalinity and total ammonia, Salifert for Mg and nitrate, D-D Merck for phosphate, and SeaChem for toxic ammonia. These are kits I have used personally over many years and find them accurate and consistent. I have heard a lot of good things about the Hanna alkalinity and phosphate kits, and will replace my Elos alkalinity kit when it runs out with the Hanna to give it a try. The D-D phosphate kit is a high sensitivity kit, is very pricey, and is probably more kit than you need when you're first starting off. In saltwater you do not need a nitrite kit as nitrite is not toxic to marine inhabitants except at extremely high levels (like <100 ppm).
Some things you won't test often and if money is an issue you can just buy the ones that are used often, then take a water sample to your LFS for the tests you don't perform often. You will often test calcium, alkalinity, and magnesium. You will test ammonia, nitrate, and phosphate much less often.