an X300. i have had an L130, which is just an older model of the LA series, and i have an X500 now. the reason, the L/LA series were designed to sell on price alone and are NOT built to last. if you are going to spend the money on a Deere, get one made to the level of quality the name invokes. if you cannot afford a X series machine, then save some money and buy a Craftsman/Husq/etc GARDEN tractor for about the same money. at least it will be a little tougher and last you for years.

do you plan on ONLY cutting grass with the machine? what about hauling/snow removal? is your lawn flat and smooth or rough/hilly?

yeah it will only be grass....and its all flat.
I would consider the x300 but thats a little more then i want to spend.

then get the biggest model you can in the la series. i say that because it is better to slightly overbuy and under use, than to under buy and over use! the equipment will last longer, though the LA series is not intended to be a 15 year mower.

As far as "handling it better," the two machines you've listed will be equal; the biggest difference is that the LA145 has a 48" deck and electric PTO. Otherwise, they have the same engine and transmission. Therefore, I'd go with the LA145 for the larger deck - making sure, of course, that the 48" deck will go through any gates that you have.

As far as longevity, a LOT of that depends on the care that you give the machine. I have a 15-year-old Deere STX (a distant ancestor of present low-end Deeres)that's still going strong (it does have a Kohler 12.5HP engine, rather than B&S.)

I would suggest that you have a look at the Husqvarna offerings. My 3-year-old Husq LGT2654 is a well-built machine, with which I'm quite satisfied ... time will tell if it will last as long as my old Deere STX. (By the way, Husqvarnas are virtually the same as Sears Craftsman machines.)