I was looking around on the Simv site and i found two aircraft:
#F-15
#Mig-21
there are different packages. But i cant choose. what are the best packages of those two?
It's quite simple in fact.
For the F-15, the best package is the ex-payware from IRIS. You'll get the Eagle and the Strike Eagle, with nice external models and very nice virtual cockpits.
There is another F-15, made by CORAL, but it's really old now and cannot be compared visually to the IRIS Eagle. So go for the IRIS ones. I don't know if they have been uploaded to the SimV libraries, but you can also download them directly from the IRIS website.
For the Mig21, it's even easier, since there was no good freeware Mig21 at all until very recently (two years or so). Basically there are two birds that you should absolutely download:
1 - the Mig-21 F13 by Jan Moravec. Although it's in FS9 format, it works perfectly in FSX. This is the old variant of the Mig21, smaller and with buble canopy. The model is beautiful, the virtual cockpit is awesome and extremely clickable. The checklist to start the engine is quite complex, and I advise you to watch this video to learn how to start it:
[media width=600]http://www.youtube.com/watch?v=fjkBYZ7oGmg[/media]
2 - the Mig-21 MF by Ivan Jurcaga. This one is real native FSX format (self shadows etc...), and is on the same level of quality than the one above (with some additionnal goodies). It's the "modern" variant of the Mig21, a bit bigger and more powerfull. The external model is awesome, the VC is fantastic, and just like the other Mig21, you need to read the documentation in order to be able to start it. I recommend you this video:
[media width=600]http://www.youtube.com/watch?v=_yl8yiEuQBg[/media]