A key issue is the chamber's throating and resulting COAL. The 284 was originally introduced by Winchester in 1966 as a short-action cartridge with 2.800" COAL same as the 308 Win. This limited it to 140/150 gn bullets, but the intention was to give .30-06 MVs for 150s in SA rifles/ Not a great commercial success.
In the 80s/90s some US long-range deerhunters started to have long-action rifles rebarreled in 284 throated to allow 175gn class bullet seated optimally. It was unofficially named the 284LT (for 'long throat') but is in effect a wildcat like this. This century match shooters discovered it in this form and adopted it in single-shot rifles using 175-180gn + weight bullets. The 180gn Berger Hybrid is the most common match choice, some use the same weight Lapua Scenar happily with good results. ELD-M, can't say as I've not heard of any use of it. The ELD-Ms in general terms have acquired a mixed reputation across various calibres, some getting very good results others not managing to get them to shoot well at all. If you're looking to use this design and in a sporting rifle, the 162gn model which replaced the old AMax of this weight may be a better choice than the 180. For match / steels etc use I'd recommend the elderly but still very effective and easy to tune 175gn Sierra MK - cheaper than ELD-Ms and Hybrids as well.
For 175/180s, popular powders are RS60, N165, H4831sc (no longer with us of course) IMR-7828 (same for this one). Norma 204 and URP should work but I've not heard of anybody trying them. Alliant Re19 and 22 give good results but are very temperature sensitive so match shooters avoid them. The new temperature unaffected Re23 may be a good option, but it's so new here that most people haven't even heard of it yet. H4831/IMR-4831's replacement from the Hodgdon stable is IMR-4955, but I've heard no results and few if any dealers even show it in stock.
My personal favourite for match use with 175/180s is Viht N165 - very stable, gives high enough MVs to be competitive and has a low flame temperature so is easy on barrels. Many people really love RS60 in this cartridge, very high MVs, but it will kill barrels quickly at full pressure loads, and a proven load sometimes seems to just stop working in a rifle for no obvious reasons. The loads suggested for N165 are in the right ballpark, but only if it is a long freebore chamber and these long bullets are seated well out. You're into compressed loads at 56/57gn with necked-up Lapua brass and a powder funnel with five, six inches of drop tube and a slow pour is a good idea. I have used 57gn N165 with 180s without pressure issues, but I've also seen other people blowing primers at this level, so it's very throat and barrel make / internal dimensions specific. For 160/162gn bullets, Norma URP, RS60, RS62, N160, IMR-4451 and I would think the new Alliant Re16 that Americans are raving about as a (superior) laternative to H4350 should all work. I've used N160 happily with the 160gn Sierra acetyl-tip TMK in 284. This is an excellent 7mm bullet in this weight bracket incidentally, like the 175 SMK it is very easy to tune vis a vis seating depths and loads. However, all this is dependent on freebore / COAL and these charges only apply at ~3-3.1" COALs depending on the bullet. Shorter throating / COALs will see higher pressures and hence lower charges having to be used, and for many of the slower burning powders a deep seated bullet will in itself constrain charges because of the room the lower shank and tail section take up inside the case.