This option have different function, I think speed is the some.
AP (WDS) Option 1 allow client to connect to both AP, both AP must be at some channel.
Wds slave allow to connect to AP like client but with full layer 2 transparent bridge using wds but other can connect to the device in wds slave mode, also scan for signal based on scan list not need to be on some channel on establish connection. If you have Mikrotik device try also station bridge that allow transparent layer 2 bridge without creating additional wds interface.
It depends on situation. In case you have 2 aps connected by wds with their own cable uplink, there is almost no impact on connected client’s speed. When client’s data will go also thru wds it is similar like transferring data from one client to another via the same ap. So what is your real situation and what problem are you facing?