Hi ,
without straying from the topic
1. Best model currently : EM1 , it just won 4 awards at the digital life awards and awarded product of the year at DPreviews if this matters to u.
If u r into video , get the Pana GH series. If imaging more, get Olympus.
2. Olympus vs Panasonic - , the built in IS in Oly bodies is an advantage unless u r looking at GX7, the only model in Pana with built in stabilization.
3. Lenses to start, u've a good budget: I actually won't suggest the EM1, the weight may be an issue to u.
To start, u can consider the EP5 , EM5 (elite ) or EM10 (to be released in this or next week) . The EPL6 or EPL5 is also worth considering if u r on a tight budget.
Lenses: I suggest getting a fast zoom and a prime to start with, if budget allows , throw in a longer range zoom and slowly work your way up. A good zoom will be either the Pana 12-35/2.8 or Oly 12-40/2.8. Excellent primes are the 12/2 , 17/1.8 , 45/1.8 , Pana 20/1.7 and so on and on.
As a beginner to MFT, I will suggest u get the EM5 with a 12-35/2.8 or 12-40/2.8 and a prime of your preferred focal length to start. For $3k , I can buy at least an EM5 (elite) body + 12-40/2.8 and a 45/1.8 with change and do street, portraits with no problems.
MFT's strength is that it has a large range of lenses to choose from , unlike the A7/A7R which has only 3 native lenses currently. No doubt a FF is a draw for many, the lenses don't come cheap.
Lastly, go take a peek at the photo sharings at the MFT forums for an idea , I own the EM1 ,EP5 , 12-40/2.8 , 17/1.8 , 45/1.8 and a 7-14/4 and don't really find a need for more lenses.