There is no "best" ... you have to decide which option works for you.
If you still have your serial number to Lightroom 3, you can pay the upgrade price instead of the full version price.
If you already own Lr3, you don't need to pay for a full version - you can buy an upgrade.
* if you don't need/want Photoshop nor Lightroom Mobile, just buy the "boxed" (stand-alone) Lightroom upgrade - see 'Products' link at bottom of page trying to get you to subscribe to cloud version.
* if you do need/want Photoshop too and/or Lr Mobile, just subscribe to the Photography cloud plan..
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