I went ten years (the lender wanted 15 but I argued it out) at under 5.03% which was nice. I scored HUGE during the low interest phenomenon. Go 15 if you can and do go for a more respectable ISD if you want a better resale potential.
I was lucky. I bought a 2 year old 4/3.5/3 house in an area that was yet to boom and eventually did. I added 1000 square feet and now my little 147K total investment has bloomed into a 300K+ property. The nice thing about our house is that we have HUGE yards. All of the new homes near us are 300K plus (up to million ranges) and have these dinky zero lot line yards. One of my neighbors bought his house a month before I did at 99K (a smaller house 3/2/2) and sold it in November at 177K. Not a bad 3 year improvement. Another neighbor of mine built his house 2 years before I got there (basically the same house as mine before my additions) and he just listed his house at 329K. I hope it sells in that range.
Good luck.