it may not exactly be meta, but everything capable of gr 100 solo is capable in some form or fashion of getting gr 105-110 in 4man if not higher with the right type of group setup. scout/buff support, grouping/buff support, and 2 dps can have lots of variation this patch.
for example just in casual speed grs, zmonk + zbarb with some globe generation + rashameteor 3mil damage and bad deathwish + me n6m4 dh 3mil damage have consistently done 95s in 5-6min. thats about what we did at same gear lvl last season prior to getting 3.5mil damage on rathmas to push 111 with znec/zdh/2rathma. you can do much higher than in the past with not exactly meta specs, it just might not hit leaderboard unless you really hit the paragon farm and setup the group to be most inclusive for your spec.
there's so many viable builds for each class, if you had to pick a class that would be better in solo push you would end up with better information than wanting to pick a build for this reason.
class-wise there's not too much difference, but necro lancer is still slightly on top and wizard with its numerous top100 level builds edge out other classes due to how viable they are in group with different roles both speedparagonfarm and push (lancer/boneringer push, rathma farm or 2-3man push, znec for same comps as rathma, wizard support for either comp or dps that is a good alternative to WD in push and makes a more standard comp almost as good as rathma at paragon speedfarm)