Thunderbolt by all means! There's no way in hell I'd ever own another Motoblur device, ever! If the Bionic is rolled out non-vanilla with Motoblur installed it'll suffer the same fate as the Atrix. The Atrix seemed like it didn't even have a dual-core processor. The Inspire & T-bolt both feel like a snappier phone than the Atrix & the Bionic will share the same Tegra 2 processors.
Plus the look of the Bionic just looks really cheap & plasticy like the Atrix does, no metallic accents like the HTC phones have, which I feel add to its premium built feeling.