Same as by Paris, I would call this more a list of nice locations, and a real Top spots list will require more visits to London (hopefully soon :) ). So for now, here is a temporary list.

To see all my photos from London, look into the London Category
Don’t forget to check out other available lists:

Tower bridge

Of course this was my first destination, and probably is for most people. Taking photos on the bridge is great, just in the area around the bridge, don’t be surprise if you get stopped by security guards. I was twice in a mater of minutes :) I would really suggest having a small tabletop tripod and a clamp as a backup, just so you can get the shots you want.

City hall area

This area is really close to the Tower bridge, and also give a great view of it. Again there is a big chance that you may be stopped by security guards (if you use a tripod) in this area, but that haven’t happened to me. Again a tabletop tripod could be real help in this area.

Westminster bridge

Surprisingly no security guards here, and a really nice view of the bridge and from the bridge. Also great spot for early morning, if you want to get a passing buss in from of the Westminster palace.

London Eye

Another spot where you should be prepared for security guards or police to stop you (that is a recurring theme in London, btw.). Still the view of the London Eye is great and the lights on the nearby trees are there all the time.

Leadenhall Market

As all the other spots are outdoor, I’m including one that is indoor. The market is only partially indoor, but the architecture is just stunning and looks wonderful. It’s a little harder to find in the middle of a very modern area, but really worth it.

 
There are of course many more (Canary wharf, Piccadilly circus, Westminster cathedral….), and I hope to update this list again
 
Other available lists: