Go to SEVERAL shops and try gear. Rent gear and dive it before ya buy it or try it in their pool. Try steel tanks and alum and see which ones trim out best for you. Ive owned 5 dive knives over 15 years and the best one is a 5$ ss bait knife with a line cutter,serations,and a razor sharp edge. Locking sheath included. Does everything my 100 knife did just alot cheaper and when i lose it i dont care. Point is look at LOTS of different gear and see what works best t for you. Theres alot of pricey JUNK out there. Dive shops only carry certain brands and will try to sell you that theirs is the best and the rest is crap. Ive got 5 complete rigs. I am a gear whore and i have a problem but i dont drink or smoke so better scuba gear then crack. Have spent piles of cash on gear and have learned that what works best for you is what worth payin for. Dont base your decision on what others recommend unless you can try it first and it works for you. Make a list of what you need. What you want. Then work from there.
Dive safe