While seasons 1-4 are excellent, if you want to catch up with the latest episodes quicker I could definately recommend starting with season 5. Its a new guy playing the doctor, and a new lead writer, meaning that its basically like starting again. If you've watched no Doctor Who previously, there might be one or two things you don't quite understand, but you can pick it up quickly.
Another reason I'd start with season 5 is that the first episode of that season (The Eleventh Hour) is possibly my favourite episode ever - a lot happens in it and its just really enjoyable. That said, if you're happy to start a bit further back, Season 1 is the way to go - just don't be off with the first couple episodes, I found that that season took a while to get good unlike some others.
I'd also recommend not getting into old doctor who before you've watched all of the new stuff. it hasn't really aged well, so make sure you love the new doctor before going back to it (you don't need to see any of it to enjoy the new doctor who from Season 1).
Another reason I'd start with season 5 is that the first episode of that season (The Eleventh Hour) is possibly my favourite episode ever - a lot happens in it and its just really enjoyable. That said, if you're happy to start a bit further back, Season 1 is the way to go - just don't be off with the first couple episodes, I found that that season took a while to get good unlike some others.
I'd also recommend not getting into old doctor who before you've watched all of the new stuff. it hasn't really aged well, so make sure you love the new doctor before going back to it (you don't need to see any of it to enjoy the new doctor who from Season 1).