There is no reason to pick Syndra right now with Veigar existing

Both have spammable q's. Except Veigar's does more damage and grants free ap on minion and champion kills and assists. At lvl 9 when Syndra maxes her q it'll start doing (and I shit you not) 4.5+9% ap more than veigar's.

Both have an aoe nuke for a w. Syndra's has the grabby mechanic which is useless unless youre contesting jungle creeps, and a slow. Veigar's has a delay which is effectively negligible with his stun that is easy to land. Hell it's ez to land this thing without even stunning them so long as they're just trapped inside.

Both have a aoe stun for an e. Syndra's does damage, but requires the use of two abilites, compared to Veigar's one. Veigar's is easier to land and while syndra's is a static 1.5 sec, veigar's starts at 1.5 sec and scales up from there.

both have a point-and-click ult. Because any good syndra won't use her ult unless she has at least 2 dark spheres out coupled with the 3 around her, her ult is more like 450/675/900 +100% ap. I say 2 because in the middle of teamfight or a skirmish having more than 2 out won't really be a possibility until she has 40% cdr. However so long as veigar's target has more than 500 ap (past lvl 16 mind you, this number goes down at levels 11 and 6 to 375 and 250 respectively) will actually do more damage. Which is pretty stupid considering while syndra has to setup her ult, veigar literally just has to press r.

I won't even get into how Veigar's passive is useful at all stages of the game while syndra's is useless up until lvl 9 and really is only effective at lvls 9 and 16.