I think your choice may come down to how you want to use them. If you are planning on canning a fair amount, bush beans are probably the way to go. You can get a lot of production over a short span. If you just want a few to eat on during the season, pole beans may be your answer.
Since you are asking about space efficiency, you possibly don't have the room, but if you can, try planting a few of each type and see what you think. You have a long growing season in Austin, but the summers can be fairly dry. You may wind up doing a lot of watering, especially with pole beans. You and your water bill may be happy to have the production over and done with bush beans. But I really like fresh green beans from the garden all season.
I do mostly pole beans since I use my garden fence for the trellis. I'll can what I need then keep one section picked and watered to produce beans for the table all season. The rest I let go to seed and use those for dried beans.
Last summer my bean production was weird, due to the unusually hot dry summer. My bush beans (Black Turtle dried beans) made before the heat set in, but the pole beans (Blue Lake for green beans) did not. I usually have all the green beans canned I need by early August. This past summer, I had to water the pole beans all summer and did not get my first green bean production until October. With all the water I put on them during the hot dry spell, those were expensive green beans. This year I'll have some bush beans for green beans.