The Nexus is on backorder, and isn't available in lebanon, or in any shops else where! To buy a brand new phone, you have to be an android developer with a developer account (some fee required) then you have to have order the phone from Google to deliver it to lebanon for you. I say your best chance is ebay with a second hand nexus. (u might find brand new ones if ur lucky!)
I say go for the Desire, it is exactly the spec as the Nexus, the only difference being the HTC Sense, which can be turned off anyways. The desire will be updated to Android 2.2 any day now and with the JIT enabled, trust me u won't be noticing any lag wat so ever.
U mentioned the Galaxy (I'm guessing u mean the Galaxy S, coz samsung also released a Galaxy a while ago).
The Galaxy S, in my opinion, is definitely one of the best phones made so far! it has the best GPU and 1GHz CPU. The specs are heavenly. The only downfall is the Custom UI (The TouchWiz) which makes it look like a crappy iPhone clone!.. Alot of pple don't mind the touchwiz, so it's a personal choice. i prefer vanilla UI (default android)
Here in sydney, they just released the Galaxy S, i reviewed it last week, and it's amazing! the SPEED is WOW! the graphics is so cool. it also has TV out with it's 3.5'' Jack. I just hated the UI. But with pple like Cyanogen with Custom ROM. I'm buying the phone, then root it and load CM roms.
If you want to buy an Android, and ur a geek, u have to look into loading up ur own ROMS they are real sweet.
http://www.cyanogenmod.com/ check it out.