Define your limits on what materials you generally drill into with the set you have, and also a price point. Cobalt drill bits are great for me, but overkill for many others if they only need decent High Speed Drill bits.
I have both fractional and Number sets since I need that much more of a hole diameter adjustment ability for what I do, but most people can do just fine with a Fractional Set.
125 or 135 degree points will start easier, but 118 is the standard and probably cheaper due to being more common.
Who to buy to from.... Mc-Master Carr, J&L Industrial Supply/MSC are two companies I buy from since I can also get replacement drill bits or taps as they wear out or break to restock in my sets. They take credit cards and you don't need own a business like when trying to order with Grainger which is I think still only wholesale.