I just bought the G-20 as I too wanted to get a 10MM.
I was very interested in the XD ,but already owned 8 Glocks so it was a no brainer when a used one came along at a reasonable price.
After I get LOTS of T&E on the G-20,I will decide if I 'need' to get a different 10MM by another maker.
But I expect to like the G-20 as I shoot Glocks pretty well.
I've never shot a Glock, I imagine I'd like them. Eventually I'll at least have to buy a G19 as it's iconic now.
I went with the XD/XDM platform because of the grip safety - with a little bit of a gut, AIWB carry works for me especially while driving (years ago I carried crossdraw for the same reason, but a crossdraw that an old man's cranky shoulder can reach and still conceals well has pretty much been Unobtanium. I have a very nice one for a 1911 - but it still isn't concealable under anything less than a winter coat. As to the Glock vs XD series, It's cheaper to get a better trigger on a Glock and they're a well-proven gun as to reliability, but I have 3 XD/XDM and haven't had a single failure with any of them.
To me, especially at my age, I realize my potential weaknesses. I like to build consistent gun-handling habits and I've switched my carry guns completely from 1911's to XD(m)s so whatever I may need to use defensively it will operate exactly like all the others I commonly lay hands on. Target guns are another thing and I'll continue to shoot my 1911's at the range because I enjoy them, but as my body sags I find AIWB better and some/most modern striker-fired guns don't have that sharp butt (end of the mainspring housing) to contend with as I find it more difficult to conceal that "feature" in that carry location. Of course, I could either buy a rounded-butt 1911 or have mine professionally altered to have that feature or buy a new one built that way - but that's pricey and I could have another, more suitable gun for the same bucks. For years I mostly carried one of two guns - a Python for my work as a surveyor when we worked in copperhead-invested areas (the survey line goes where the line goes, damn the snakes!), or a Gold Cup for defense. Oddly enough, I usually carried both in an El Paso Saddlery Tom Threepersons crossdraw on a separate 2" gunbelt, as I always had a bunch of junk (survery notes, maps, etc.) hanging off my right side.
Now I realize I'm not as sharp or quick as I was then and may not mentally "switch gears" in an emergency as easily, and I think the smart thing for me to do is to stay with one platform except while at the range just having fun. If it weren't for the lack of some sort of safety besides the trigger I'd have gone with Glock, and I could have had a 10mm much sooner. I like the XD grip safety, it's familiar to an old 1911 shooter. The big bonus is that when carrying AIWB in a soft-ish holster, I can easily keep the web of my hand off the grip safety, and re-holster safely without looking down at my belt.
My latest is an XDM in 10mm. I've wanted a pistol in that caliber since the days of the Bren Ten, but I didn't trust the early Delta Elites. Besides, the Glock and XDM have more magazine capacity in a package I find easier to conceal. I didn't even get to shoot it yesterday as I'm waiting on a date for back surgery and just wasn't up to it, so I sent it with a buddy to help break it in. He came back with some impressive 10yd silhouette targets. Surgery should be soon, and I'm sure that will take a lot of variables out of my shooting - on a really bad day I look a lot like Barney Fife. At least I still have good trigger control, and know not to shoot if my sights aren't aligned - more than I can say for ol' Barney.