Tse/Pc, long macro, sensibly priced 70-200 F4 or F2.8, Super Teles (as previously mentioned), affordable longish primes (200/300/400mm), decent auto focus (except,perhaps, in one expensive body), reasonable batteries, higher voltage batteries (to drive lenses better), weather sealing (they are far from the best), no bodies with an integral vertical grip, good and fast support/repairs, a camera that is robust enough for use with heavy lenses (if and when they get around to making them), optical viewfinder (I was very disappointed with the A7R and Mk2) - shall I go on? Note this is just off the top of my head, I could do some research?
I did try out the Sony system when the A7R came out, and again when the A7R2 came out but the combination of lack of lens range, horrible user interface, poor battery life (now being addressed) and lack of versatility put me off.
Now we have a Sony body that looks very promising (well at least from the specs) - but at a grand more than my (new) 1DX was????
Sony bought one of the best lens families going but what on earth have they done with it? They bought an excellent camera system (that just needed investment) - doesn't seem to be much happening there either.
We all have different needs and Canon/Nikon strive (not always successfully) to meet the needs of the widest range of users - for now Sony don't. In other words not serious - yet.
If the Sony system suits you and your needs then great - use it and enjoy it. For me and the majority of photographers that I know they have little to offer.
Not having a go at anybodies views/opinions just relating my experiences. If yours differ that is fine.
Life is for living, cameras are to capture it (one day I will learn how!).