My daughter just would not latch on, (no probs with DD2 who came out with her mouth open!!). I expressed every feed for 5 1/2 months for DD1, by which time I had enough surplus milk frozen to last till just over 6 months, so I was using the pump very heavily.
I started with a manual pump, having intended to breast feed and only express if going out on occasion, and seriously after 1 day my hands were in agony!
My DH then bought me a Medela Swing, but it was very slow, especially once DD's milk intake started to increase after the first couple of weeks.
We then went for a Medela Lactaline double pump, coupled with a hands free bra, see www.expressyourselfmums.co.uk/Expressing-Bra (the most appalling piece of underwear one could ever own, but useful!!!) and I was amazed at how much easier and faster it made things - less than half the time of my previous pump. It was fantastic, also the bra meant I could read a book, hold a cup etc while expressing :). Ameda make many of the hospital pumps, so it is very solid and good quality, though admittedly not as pretty as the Medela pumps, for example. I have huge boobs, and the Ameda pump had inserts you can buy to cater for different sizes and shapes, which made it much more comfortable! The current version of my pump is www.expressyourselfmums.co.uk/Expressing-breastmilk/ameda-lactaline-breast-pump.htm
The Express Yourself Mums site was really useful in helping to select products, has various articles about feeding and expressing, plus product reviews. They have a very comprehensive range of pumps to buy, plus rental ones (I know you want to buy one *Moomin, just mentioning it in case anyone reading is looking to hire), and accessories such as spare bottles and insulated bags for taking the pump out and about.
Good luck choosing!