Angled eyepiece is by far the most commonly used. I did use a straight eyepiece scope though and it was OK. Looking through a straight eyepiece scope from a sitting position (if you score from a sitting position) would be much more difficult than an angled eyepiece.
Adequate eye relief is a must (whether or not you wear glasses) and so is a reasonably decent field of view. Cheapy scopes usually fail this, badly (but check).
Absolute waterproofness is nice. Many expensive scopes that claim to be "waterproof" (I'm looking at you, Kowa) actually aren't.
Don't need any more than 25X-ish magnification (even if that sounds difficult to believe). My spotting scope is a fixed 22X. Other common magnifications are 25X and 27X fixed. Variable is not necessarily bad, but I've never looked through a 15-60X scope that told you more at 60X than it did at 25X.
You'll need a scope stand. That Rayvin looks gorgeous (that style is usually called a "bipod" because it has two folding legs; sure doesn't look like a rifle bipod eh?). A Freeland is an older version of the same idea.
If you will only be using your scope from a prone position, then the best scope stand is one that is small, light, and stable. All you need to do is to be able to hold the scope anywhere from 4"-10" from the ground - you don't need long heavy legs to do that well.
If you will be using the scope from a sitting position (e.g. coaching from a chair), you need a taller scope rod and possibly a stand with larger legs so that it is stable with your scope 20-24" high. If you are going to shoot from a standing position like the Americans do, you'll need a much larger and heavier tripod-legged scope (oftentimes they also have a spike in the middle too). As spotting scopes have gotten larger and heavier over the years (e.g. you see big 77mm and 80mm scopes these days, vs 60mm being a "large" scope 20 years ago), the need for larger and heavier scope stands has grown.