Everything in FX is relative

"The US economy is strong" is not a trade. "The US economy is strengthening faster than the euro area, and the market has not priced that" is a trade. Currency pairs are a comparison, so your analysis has to be comparative.

A simple relative scorecard

You do not need a full econometric model. Score each economy on a handful of dimensions, all expressed as direction and momentum rather than level:

Growth momentum — is the PMI trend rising or falling?
Inflation persistence — is core inflation momentum accelerating or decelerating?
Labour market — is employment momentum improving or deteriorating?
Policy direction — is the central bank tightening, easing, or holding, and what is priced?

From scores to a pair

Difference the two economies' scores. A large positive gap favours the first currency. Then — and this is the step people skip — check whether the gap is already in the price. If the market has spent three months pricing this divergence, the trade is crowded and the remaining edge is small.

Divergence is not enough on its own

Three things can override a clean macro divergence:

Risk regime — in a global risk-off move, the dollar's haven bid overwhelms rate differentials.
Carry and positioning — if everyone is already long the high-yielder, the unwind risk dominates.
Valuation — a currency can be fundamentally favoured and still expensive.

The honest caveat

Simple scorecards are crude. They ignore capital flows, terms of trade, and positioning, all of which matter. Use them to generate and organise a view, not to size a position on their own.

How to check this yourself

Score the US and the euro area on four lines — growth, inflation, labour, and policy direction — from minus two to plus two. Difference the scores. That is your pair ranking, and the wider the gap the more room the currency pair has to move. Redo it monthly; the ranking changes slowly, which is exactly why it is useful.