Trading at GS/MS/JPM or Sales & Trading at Jane Street/Citadel/Two Sigma

I am quite sure you mean institutional sales in JS, citadel securities/2sig securities. THere is no sales and trading intern at hedge fund..

anyway these S&T in prop shops are like the sales trading division of banks, JS already has been doing that for ETFs while Citsec recently dived to fixed income trading and expanding their institutional services to bond investors so assuming FI sales in that division. (2sig securities no idea what they're doing) I am not sure what you want to do in the future but believe me these Sales traders in Prop shops have close to 0 chance of lateraling to quant traders in the shop. While not even sure they can move to sales trading at the banks after that, while vice versa I have seen a lot of cases..which is quite obvious because the shops usually want the experienced Sales/sales traders from bank if they want to initiate the institutional business. 

If you do the trading SA in BB, assume probability of being macro trader is roughly 50%..just assuming normal distribution. After you make FT trader and grind for quite a few years you have good opportunity to exit to these prop shops/HFs macro trading seats. and this is just my personal view but at that time these shops would also attempt to expand their business to credit..very few successful shops are already initiating this business:) you would have great opportunity then. WOrst case scenario you don't get return offer you can still apply for FT trader role. It's important to have trading SA if you want to apply to FT trading seat either in prop shops or top banks. Next year job market can't be worse than this year I believe/hope.. 

So I would choose BB trading SA for longer term optionality when comparing with Sales division in these top prop shops. 

P.S: trust me..these trading/coding bootcamp they provide with quant trading interns means close to nothing in your resume nor skillsets if its aimed to leverage for opening doors for prop trading shops.