They are really different animals. 17 HMR is of course a rimfire cartridge. It will be cheaper to shoot than the 17 hornet, unless you reload the hornet.
The hornet launches its projectiles about 1,000 fps faster. I can't speak to accuracy of the hornet, but my Savage in 17 HMR is an absolute tack driver at 100 yards. Unless the wind is blowing.
The WSM is living in fantasy land, so far. The round sounds very nice on paper but both guns and ammo are hard to find. The butt-ugly Savage BMag has already earned a very unSavage-like reputation for POOR accuracy. The other options are a high dollar Winchester Low Wall or semi-autos by Volquartsen and Franklin Armory. I think the BMag is the only one that's really on the market. Looks cheap, feels cheap, and shoots poorly. There are many reports of them shooting so poorly they were sent back to Savage.
OTOH, the .17 HMR has proven to be accurate in all of the many rifles chambered for it. I just got a brick of Hornady 17 gr ammo for $118 shipped. I think the .17 Hornady Hornet will be a great little round but ammo is in short supply and brass might be a problem for reloaders for a while. I shoot a lot of .17 HMR and .17 Fireball and love both of 'em.
What range do you want to target shoot or drive tacks at? Both are very accurate rounds with many platforms to choose from. 17HH can be as cheap as 17HMR to shoot if you reload but there has been issues with the brass and factory ammo. You can make 17HH brass from 22 Hornet brass and there are many choices of 17 cal projectiles. 17HH can be downloaded to 17HMR or even 17HM2 velocities depending on what range you want to shoot at. I have seen many bug hole targets at 100 yards from both the 17HMR and 17HH. If I didn't already shoot 17 fireball and 17HM2, 17HH would be next on my list to get. The 17WSM is intriguing but lack of platforms and accuracy problems are keeping me away from it for now.
If you do not plan to shoot over 100 yards and do not want to reload then go with the 17HMR.
Yeah I have been reading up on 17 WSM on rimfirecentral and it looks like the B.mag could go either way. Some guys are getting great results, others quite poor. I found it reassuring that Savage is either giving refunds or exchanging them in some cases. Ammo availability seems to be an issue now as well. I will likely be giving it a try, but if you want a sure thing, get a HMR.
That HMR's one heck of a cartridge. I got a cheap Mossberg for varmints in the barn lot. Best round I've ever used that wouldn't cause any collateral damage, awesome for shooting around equipment. Wish I got one 10 years earlier, but I always thought it was to puny lol. I get MOA even though it's barrel's bout the size of a pretzel rod lol. I'm gonna get a Marlin or Savage with a heavier barrel
I've was pining for a 17hmr for a few years after shooting prairie dogs with one. Finally got a marlin with a heavy barrel. Shoots great. Sold my 22 for varmints!