Curious about one thing: do you vlog while walking? In my experience, IBIS doesnt fix heavy footfalls, so I'd be cautious skipping the Tamron 17-70mm f/2.8 Di III-A VC RXD for handheld video tho.

1. Quick question—u shooting handheld video?
2. I hated how the bulky Tamron 17-70mm f/2.8 Di III-A VC RXD felt, so honestly, stick with Sigma 18-50mm f/2.8 DC DN Contemporary!

Ugh, I am literally going through this exact same dilemma right now! I've been staring at my cart for days trying to decide on a zoom for my a6700. It is so frustrating trying to find that one perfect lens that doesn't feel like a brick but still performs when you're out and about. I've been doing a ton of digging into reliability because I hate the idea of gear failing on a trip. If you want the most reliable build quality and weather sealing, the Sony E 16-55mm f/2.8 G is basically the gold standard for APS-C. It lacks the stabilization, but the internal construction is top-tier compared to the third-party options. Honestly though, for daily shooting, the Sigma 18-50mm f/2.8 DC DN Contemporary is what I am leaning toward just because it's so tiny and won't make the camera tip forward. Regarding the video stuff, the IBIS on the a6700 is decent for micro-jitters, but if you're walking, you might still find yourself wishing for the Tamron 17-70mm f/2.8 Di III-A VC RXD. It's a tough trade-off between weight and features, but for a workhorse that'll last years, that Sony G lens is probably the safest bet if you can swing the price tag.

Gotta agree with QuinSmoth on the size thing. The a6700 is such a nice, compact body that putting a massive lens on it kinda defeats the purpose of going APS-C for travel. Ive been shooting with this system for years and usually the best lens depends heavily on how much youre willing to drop at once. That brings me to a couple of questions tho... what kind of budget are you actually working with here? Theres a pretty big price gap between the third-party options and that high-end Sony glass. Also, are you looking to buy new or are you open to hunting for deals on the used market to save some cash? Knowing that would really help narrow it down since the value-for-money varies quite a bit between these options.

Coming in a bit late to the party but I totally get what RobertEdgep is saying about reliability. It is such a headache worrying if a lens is gonna play nice with your camera long-term, especially when you are traveling and dont want to deal with gear issues. Honestly, I have always been way more conservative with my gear and usually find that sticking with Sony is the safest bet. You might pay a bit more sometimes, but you are getting that native performance and peace of mind that everything will just work. The autofocus and stabilization are always just... better when it is first-party. In my experience, any Sony zoom is gonna be a solid choice for the a6700. You basically cant go wrong with native glass if you want a reliable workhorse that wont give you any weird glitches down the road. Just pick a native option from them that fits your budget and call it a day.

^ This. Also, I completely agree with Patrickmah on the reliability side of things. I've been pretty satisfied with how my current gear works well together, but getting to this point was a total headache. I remember spending a whole night trying to DIY a firmware fix for an old lens just because the manufacturer stopped providing updates... honestly its ridiculous how they treat us.

• It drives me crazy that brands are charging near full-frame prices for glass like the Sony E 16-55mm f/2.8 G while clearly cutting corners on the internal construction.
• The size trade-off is such a scam too; you either get a compact option like the Sigma 18-50mm f/2.8 DC DN Contemporary that lacks features or a massive brick like the Tamron 17-70mm f/2.8 Di III-A VC RXD that kills the whole point of a portable system.
• Honestly, the way these companies prioritize profit margins over actual user experience in the APS-C segment is just insulting. Its just frustrating because the a6700 is such a technical beast, but the lens market feels like a mess of overpriced compromises lately... dont even get me started on the QC issues.