Do you already have a spotter or are you planning on buying your first spotter?
If you are planning on buying your first, the old saying of "buy the best glass that you can afford" is very good advise. I have a Vortex Razor HD 65 mm spotter that I really like. It's not the best one out there, but it works well for me. Straight vs angled is a personal preference, each has its advantages.
Also, you need a good tripod and head. Without a good solid platform for your spotting scope, you will not be able to utilize its capabilities. You need a spotting scope to be really still while looking through it.
You may get some more advise from more knowledgeable guys if you specify your type of hunting and terrain you are planning on being in.
Good Luck