Saying Mi Tierra is "not the best" is really quite an understatement - it's tourist schlock.
If you have been gone for 15 years you will not recognize the place. Unfortunately, there has been an invasion of chain restaurants on the Riverwalk, but it is still possible to get a good meal. Biga is OK, not the shining star it once was, but reliably OK. Boudro's is a better bet for a good meal. Bella on the River also gets great reviews, as does Lüke.
Off the Riverwalk you'll find great options in the area now called "Southtown" which you might remember as the edge of the King William neighborhood. Rosario's is a great option for TexMex on the corner of South Alamo and S St Mary's. Feast is a foodie haven a little further down S Alamo. The Liberty Bar relocated from the famous slanted building on Josephine to 1111 S Alamo in the building that used to be the convent of St Benedict's (which is now condos) and is a great place to go with a group - good, varied menu, great bar, easy ambiance and good service.
Another recently booming place is the
Pearl on Broadway with several good options. The
Arcade is one I particularly recommend, but there are other options, too.