I have the 911 in the pic. Your welcome to it if you want to come to TN.
I'd opt for a 911 of any year over the 914 then. Don't get me wrong I like the 914s, I actually go on some back roads twisties with those guys. But they aren't great performers. In my opinion, they lack the power anyone expects in a sports car. They also tend to be more prone to rust than the 911s as well. Porsche began galvinizing 911 bodies, in some say late 75, but 76 for sure, granted that doesn't deter all rust, but it helps. I don't know if the 914s were ever galvinized.
With the 914 you also get a lot of the Porsche cost with not much of the performance reward.
The Boxster will be a get in, turn the key, and drive car. It will perform better in handling, take off, and top end of the 911. But to me its just like driving any other modern convertible. Nothing makes you get in it and go "Man I love this car." There are many books out there on working on the Boxster. From what I gather it isn't a bad one to work on. But I've never turned a wrench on one.
EDIT- Woody posted the book I was thinking of.
With the 911, you get decent performance, it's not going to win any drag races if that's what your after. But the driving feel, and taking the car on some twisty roads will always put a smile on your face. You feel connected to the car and the road, whether you are driving the track, some back roads, or down to the store for a gallon of milk. They say it's a "driver's car", I don't know about all that, but I do know it is a great driving experience. Plus it has its quirkiness, but is still an easy car to work on. There are some great books out there for 911 owners, plus if you weed through the "will these wheels fit my car" threads on rennlist and pelicanparts, they both offer great sources of information on repairs and mods. I do everything I can on my car, including clutch change, motor swaps, valve adjustments, etc. The only skills I had before working on the 911 was changing the oil in my old VW bug. I'd say it is a very easy car to work on.
EDIT- There is a 101 Projects for your 911 as well. It's good (but don't do the motor drop as it suggest. Take the motor and tranny out as one unit.) Also Bruce Anderson has a 911 Performance Handbook that is good as well.
Again, I suggest you find the 3 nicest examples of each, go drive them, see what you think, and get back to us. I don't think a comparison by a bunch of internet nannies, myself included, should be the deciding factor in what car you look for. You could love the 914 and hate the Boxster and 911. You could hate the 911 and love the other two. Or you could love two and then really be in a point to decide which car is the best.
And I hate you for getting a lift. Not only do I long for one, but now that we moved I can't fit one in my garage...